Wind patterns at meteor altitudes (75-105 kilometers) above College, Alaska, associated with midwinter stratospheric warmings

A significant change in prevailing winds at the 75- to 105-km level at College, Alaska, was observed during the midwinter stratospheric warmings of 1967–1968 and 1970–1971. Neutral wind values for the upper mesosphere and lower thermosphere were derived from radar measurements of the drift of meteor trails. The normal prevailing wind at College in the winter is eastward and usually poleward. During stratospheric warming events for two winters, both the meridional and the zonal prevailing flow reversed for a period of 10–15 days. The winds above 100 km, however, did not appear to be as strongly affected during the warming event of 1970–1971. The change in the wind pattern in the 75- to 105-km level occurs about the time that the circulation breakdown begins at the 10-mb level.